File system cloning is an improvement over traditional file copy and back-up operations. During a file system clone, the data underlying an existing file system are examined at the physical media layout level, and a stream of data is created representing that file system. A new file system is then created by initializing and modifying low level file system structures directly on a target physical medium. Because it operates at a lower level, a cloning operation is more efficient than traditional file copying operations. Additionally, cloning operations can leverage knowledge of physical media architecture, and can access file system metadata.
Cloning is a destructive process, which overwrites whatever content may happen to be in the target region of the physical media, by laying down a new file system thereon. Although cloning is an efficient way in which to create a new file system with the content and attributes of an existing one, as it exists in the prior art cloning cannot preserve files or directories that are already in-place on the target media.
Traditionally, in-place files have been preserved during destructive operations by moving the files to a different physical location for the duration of the operation. After the successful completion of the operation, the files are restored. Copying the files to a secondary storage medium and then restoring them after a destructive operation requires time. Where the number of files is significant, or where individual files are very large, the required time becomes substantial, as does the free space requirement on the secondary storage medium. Additionally, this technique requires an accessible secondary storage medium.
What is needed are methods, computer readable media and systems that provide preservation of in-place file system objects during cloning operations.